geefer,
You didn't say where you are located and that makes a big difference in my opinion, because unlike LV drives, MV drives are something you want really good technical support on. Of the ones you mentioned, I would think that if you were in Europe, Siemens and ABB would be better choices, but if you were in the US, all 3 would be fine from that standpoint.
By the way, you left out Toshiba, also one of the premier MV VFD manufacturers. I would consider them over A-B if I had to limit your choices to 3.
To be fair, I work for Siemens, albeit a different division. But in my prior life, I did a lot of projects with MV drives on them and I have worked side-by-side with the technicians commissioning drives from all 3 of your choices. I would pick the Robicon hands down every time. I also used to work for ABB Drives Div. in the US and they had a complete overhaul of their MV drive product line in the last few years because it was not getting the job done in the marketplace. I have not heard anything bad about their newer ones however. At one time, ABB was making the large drives for Allen Bradley, but now Rockwell makes their own in Canada, which means they are a relative newcomer in the MV VFD world.
Component count means little. Reliability means everything. Ask for end user references, especially ones in your locale.
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